1. Field of the Invention
The invention relates to a process for granulating and comminuting molten material, in which the slag melt is acted upon by compressed water and discharged together with at least a portion of the vapour formed, as well as a device for carrying out this process.
2. Prior Art
Metallurgical slags of suitable chemical compositions are frequently granulated, i.e., quenched with water out of the melt flow with a view to largely preventing crystallization by rapid solidification and obtaining an amorphous glassy granule structure instead. Such granulates are valuable raw materials for the production of hydraulic binders. The production of such binders calls for the additional steps of drying and fine grinding the granulates, and hence two further energy-consuming processes.
Austrian Patent No. 400 140 has already described a process for granulating and comminuting molten material and grinding material as well as a device for carrying out this process, in which the melt is introduced into a mixing chamber under pressure and compressed water vapour or water vapour mixtures are nozzled into the mixing chamber. Due to the rapid expansion a pressure was built up in that known process, which, via a diffuser, caused the rapid ejection of the solidified particles. The kinetic energy of the rapidly ejected particles in that device could be utilized for comminution, wherein the jet emerging from the diffuser could be directed against a baffle plate or a jet emerging from a further diffuser. As in contrast to the conventional granulation of molten blast furnace slag with water, such a mode of procedure enables the slag melt heat to be thermodynamically and technically utilized in a better way. By cooling in water, the low temperature heat developing can be utilized to an insufficient degree only. The same applies for the known cooling of molten steel slags by giving off heat through radiation or convection. The use of compressed water for acting upon slag melts while simultaneously utilizing for comminution the kinetic energy gained in that manner has already constituted an essential improvement in this respect.